I've managed to get a couple of zones installed between other projects, and so far I am very happy with it. I'm using it with their ceiling speakers at the moment, and the sound quality is more than adequate for my ears. Volume is also plenty adequate, though it wouldn't drive the neighbours to complain!
The keypads look good, and my only complaint would be that it can be hard to tell from an angle which volume LEDs are lit and which are off. The power button can be a touch slow to respond, so sometimes I've hit it multiple times (which mutes the zones).
The amplifier/controller itself looks and feels very well built -- though it is bigger & heavier than I was expecting. It overhangs a 16" shelf .. though the feet fit on.
Installation couldn't have been simpler ... the only problem was finding a spot in the ceiling between the joists/strapping/plumbing/wiring to fit the speakers!
The serial port control works well using their software, though the software has a non-standard UI (the window doesn't appear in the task bar, so tends to get buried). The protocol itself is binary not ASCII. It looks easy enough to integrate: send command and get back state, but I couldn't trivially work out the required COM port settings to allow other software to talk to it. Either it needs a few more hours, or documentation from HTD.
I've not plugged it into my Kill-A-Watt meter ... I must remember to do that to get a handle on what its standby usage is.
I don't have any practical experience with other systems, but this one does what I want very well, and does it at a great price point.
